In mobile radio communications, a parallel operation of radio access networks (RAN) of different types of radio access technology (RAT) like LTE (Long Term Evolution), 2G (GSM/GPRS) and 3G (UMTS/HSPA) networks may be needed. Between these different RANs, inter radio access technique (inter-RAT) operations may be carried out, for instance, coverage limited handover between overlaying radio access networks. In this field, SON (self optimizing networks) and in particular MRO (mobility robustness optimization) may be used for inter-RAT mobility or load balancing between different RATs.
The target of MRO is to optimize those network configuration parameters (for example handover (HO) trigger parameters, HO thresholds or timers) that radio link failures (RLF) due to handover are reduced. In order to make the right decision in terms of parameter optimization more detailed root cause information is needed. Commonly, the optimization of network configuration parameters in 2G or 3G networks is based on labor- and cost-intensive drive testing. For the first roll-out network-wide default configuration parameters are used and if PM counters are accumulating RLFs or even call drops in a certain service areas, several optimization loops with drive testing are started to adapt parameters in a cell-specific manner.
There may be a need for providing mechanisms where cell-specific parameters are autonomously optimized to reduce high costs and the huge effort.